We have cathedral ceilings in the house (the ceilings are slanted), so there's only about a foot between the inside and outside (no attic). If I were to hide anything there I'd have to slip it through a roof vent or something...
Looking at the photos there is one thing that struck me though. I didn't know the backdrops were actually painted in B&W in those days.
I always thought they were in color and painted in a style similar to that of matte paintings used in movies.